How to write a program that performs the following task: Given an arbitrary XML document, reverse the order of all elements, pre-serving parent-child relationships. If an element contains more than one XML attribute, the order of these should also be reversed. The program should act as a UNIX filter, taking a UTF-8 encoded XML document on standard input and publishing the reversed document to standard output. Example: $ cat input.xml <?xml version="1.0"?> Hello world Goodbye world Fred & Ginger Test XML document $ cat    More>>